The proposed research involves investigations into the development of new methods for the direct functionalization of specific heterocyclic systems. Each will be subsequently examined for its potential use as a latent dipeptide equivalent, and applied as such to the synthesis of the cyclopeptide alkaloids ('phencyclopeptines'). These natural products show considerable promise as ionophoric agents, in addition to other biological activity. Particularly intriguing is the extension of these concepts to the preparation of macrocyclic lactams and lactones. Appropriately substituted heterocycles are to be studied as alternative routes to these types of compounds.